1. Field of the Invention
The invention relates to methods and apparatus for oil field management. More particularly, the invention relates to methods and apparatus for remotely monitoring oil field reservoir data in real time.
2. State of the Art
During the production of fluids such as hydrocarbons and/or gas from an underground reservoir, it is important to determine the development and behavior of the reservoir to allow production to be controlled and optimized and also to foresee changes which will affect the reservoir in order to take appropriate corrective measures.
Methods and devices for determining the behavior of underground reservoirs, for example by measuring the pressure of fluids, are well known in the prior art. It is known to locate a pressure gauge at the bottom of a production well and connect it to the surface by a cable or other communication means. It is also known to generate a pressure pulse in one well and measure the change in pressure in a nearby well. With these methods, it is necessary to carry out extensive model fitting and complex calculations to determine the behavior and properties of the reservoir.
U.S. Pat. No. 5,467,823 discloses methods and apparatus for long term monitoring of reservoirs. The methods include lowering a sensor into a well to a depth level corresponding to the reservoir, fixedly positioning the sensor while isolating the section of the well where the sensor is located from the rest of the well, and providing fluid communication between the sensor and the reservoir. The apparatus include at least one sensor responsive to a property (e.g. pressure) of fluids and means for perforating a cement layer to provide a channel for fluid communication between the sensor and the reservoir. The methods and apparatus provide a long term installation for monitoring an underground fluid reservoir traversed by at least one well.
All of the known methods and apparatus for monitoring reservoirs require that the data be analyzed by human experts in order to interpret it. This analysis typically occurs on site, requiring human experts to travel from one site to another in order to interpret oil field data. It would clearly be advantageous to allow human experts to access this data remotely, thereby saving otherwise wasted travel time.
Communication systems are known in the art whereby oil field data is transmitted to a central location for analysis. For example, the WELLWATCHER™ system from Schlumberger continuously transmits (via satellite) subsurface sensor data to a centrally located analysis and data repository center. Although the WELLWATCHER™ system provides many advantages, there remain several disadvantages of oil field data analysis which are not addressed by the WELLWATCHER™ system. One apparent disadvantage is that the “central location” may not be conveniently located for all of the human experts involved with a particular oil field. Another, less apparent, disadvantage is that there is too much raw data.
One of the disadvantages of oil field data analysis that has gone largely unaddressed in the art is that most of the analyzed data provides no important information, yet requires as much effort to interpret as the data which provides important information. This is to say that, more often than not, the analyzed data indicates that the oil field is producing at an efficient rate and there have been no changes in the reservoir requiring corrective action. As a result, human experts analyzing oil field data spend most of their time analyzing data that provide no new information about the reservoir.